Combined fuse



Patented `lari. 3, 1950 UNITE COMBINED FUSE Willi Weiss, Vernier, Geneva, Switzerland, as-

signor to Brevets Aero-Mecaniques S. A.,

neva, Switzerland, a corporation of Switzerland Application December 18, V1945, Serial No. 635,695 In Switzerland January 17, 1945 2 Claims.

The present invention has for its principal object the provision of a fuse having an angular velocity detecting device of extremely reduced manufacturing cost and affording a high degree A of reliability in its operation, resulting from the fact that relatively large centrifugally controlled Among these fuzes, there exists a whole class in which the setting-off of the explosive action is produced entirely mechanically. These are referred to as combined mechanical percussion and self-destruction fuzes. In the known types of this class, the automatic setting-off of the explosive action causing the self-destruction is generally obtained either by the action of clockwork such as is utilised in the mechanical time fuzes or by the action caused by the decrease of angular velocity to which the shell is subjected while following its trajectory.

In this latter case, a device is used which functions as an angular velocity detector. This device consists in one or more movable elements located in the fuze, and which shall be referred to below as the centrifugally controlled elements. These are subjected to the opposing actions exerted on one hand by the centrifugal forces generated in the elements lby rotation of the projectile carrying the fuze, and on the other hand by one or more pre-set springs located in the fuze. Immediately after the instant of firing, the angular velocity of the shell is so great that the centrifugal force on said centrifugally controlled elements is predominant, said centrifugally controlled elements being brought into a relative position of rest. Later, when the angular velocity of the shell has decreased to a value predetermined by calculation or experience, the spring means overcome the centrifugal force and drive an element commonly called the striker or firing pin which sets off the explosive action.

The centrifugally controlled elements known hitherto consist generally either in levers Ipivoted around an axis, or in loose bodies such as steel balls, cylinders, or prismatic bodies rounded at one or both ends, and radially movable in guiding recesses. The use of such elements has the disadvantage of allowing a very limited utilisation of the available space which is particularly restricted in the fuzes for small projectiles. It is evident, that the reliability of operation of such an angular velocity detecting device depends on the magnitude of the forces coming into play.

Owing to the unavoidable frictions, the actuating forces should be kept reasonably large. It is thus seen, why the smallness of the hitherto known centrifugally controlled elements causes a definite lack of reliability in spite of all efforts for accuracy made during manufacture and assembly, these efforts leading to a high manu-` facturingcost. an; Y.

elements are utilised. Indeed, these elementsI substantially fill up the whole annular space leftn free in known fuzes for elements having similar function together with their guiding elements.

These centrifugally controlled elements are when it is interrupted in several places its components affecting the form of ring segments, will spread apart during their substantially radialdis-r placement under the centrifugal action. In

either case, it is easy to see vthat such a ring `fills'l more completely the available annular space than spherical, cylindrical or prismatic bodies, the

mounting of which is carried out according to' common practice. Further, such a ring made of two segments, for instance, may be guided radial' ly for a distance substantially equal to the outside radius of said annular space, while usual prismatic bodies which could be utilised in the same space would be guided for a distance equal substantially to the radial dimension of said elements being represented in their relative posi-i tion of rest after assembly, that is, their unarmed positions; i

Figs. 2-5 show in detail'the interrupted ring which constitutes the centrifugally controlled organs, Figs. 2 and 3 being respectively a planA view and an axial section of a ring interrupted in one single place, Figs. 4 and 5 being respectively a plan View and an axial section of a ring interrupted in two places. y

In the various figures like elements or elements of similar function are designated by like numerals.

A fuze has a body 6 with a screw thread I3 shown) minated by a thin cover I5 maintained in place by a ring I6. A striker 'I made of two pieces placed end on end is located axially, the front' end flaring into a disc I'I, the rear end having 991' cylindrical shoulder y8 and terminating in a pin' 1f'.

When the ring is interrupted in one place or inner hollow cylindrical sleeve 5 movable axially" in the interior of a second or outer hollow cylindrical sleeve 3. A hole in the bottom ofrinner sleeve 5 leaves free passage for pinl'l'. Outer sleeve: 3l

is slida-ble axially in fuze body E and-is provided-` with an external annular groove in whicha splitring I is snapped. A hole inthe bottom of 'sleeved 3 gives free passage to shoulder 8 of strikerTY and permits the rear end of inner sleeve -to slide axially.

Aring Il made of several segments having. a bevelededgeportion cooperating with a'co'nical indented portion I2 in a cap I4, surrounds pin I'.

Inner sleeve `5 has .two spaced shoulders onits forward portion which define, along withthe surrounding.-structure,I an annular space with plane endfaces in which a circular ring vI is positionedfor free sliding ymovement between said. faces. Ring I is interrupted in one or more places and constitutes Vtherientrifugally controlled; ele-1l ments referred to'above. When the relativedimensionsl ofthe parts permit, said ring may be interrupted .in one'place only (Figs. 2 and 3), and. is assembledon sleeve 5 by being sprung open Vso as to be passed over one or the other shoulder of inner sleeve '5.for assembly, after which it is permitted toassu'me its normal shape. Under` certain conditions; itmay then still exert a slight. pressure on the wall of the lodging in outer sleeve 3... In order toavoid the 'necessity for opening. upsaid.r ring j during assembling, one of thev shoulders of inner sleeve 5 may be made as a separate piece-held in placeon said sleeve by appropriate means. When said ring is interrupted in -Several places, (twoplaoes in ligs. .1,34- and,5,) the various segments are simply juxtaposed during assembly.

Interrupterring.- I has a beveled portion 2 corv responding to a matingjsurface provided in said lodging in outer sleeve 3. For reasons made evident later in the description of the operation; it is necessary that the thickness T of interrupted ring I, measured radially', be at the maximum slightly less than the difference between the `ifnternal radius RIv of the rear part of the lodging in outer sleeve 3 and external radius R2 of inner sleeve 5 between its shoulders.

In vthe relative position of the Yelements representedon Fig.j1- and which correspondsto ythe, nal Aassembly of the fuze ready for transportation and for mounting on a projectile, spring Blocks striker 1 by pressingon inner sleeve 5 which pushes shoulder 8` against annular segments `I I. Split-ring. Il] makes itimpossible for outer sleeve: 3-tofmove'forward, annular segments II being` maintained assembled by their" being urgedibyl spring 3 into the indentation I2 in cap I4'. The safety of the fuze during transportationv and handlingA is'. thus obtained.

The operation isas follows:

At the instant of firing, owing to their inertia, setback forces cause the movable elements-.to exert'a-n--axial force of reaction backwardsjon annular' segments Il securely maintaining the latter: locke'd against* capY AI 4.

During a-ccelerationthe angular velocity ofthe shell increases, and' the centrifugal' forces genr` eratedfin `interruptedl ringl, split-ring I0 and annular segments II produce thefollowing efe feats:

v`sleeve of spring 9 to said outer sleeve which rests on 4 (a). Interrupted ring l ispressed against the Wall lofithje lodging provided `inouter sleeve 3 andowing Ato its inclined'prtio'n 2, the ring grips 3 and transmits the rearward axial force said annular segments Il, this action relieving striker 'I ,momentarily from the force of spring 9;

(b) Split-ring I0 spreads open due to centrifugalforc'e and is pressed against Ithe Wall of the 'fuzeg` (c) Annular segments II (held in place so far bysplit-ring I0) tends to spread apart from each other, but they cannot do so as long as the projectile is undergoing axial acceleration, held back as theyare bythe force of "setback onthe segments themselves vand by the eiects of setbac" on members I, 3, 5, 1 and 9.

After the acceleration of firing has very substantially decreased, y and while thenrotation of the projectile is generating sufliciently llarge centrifugal forces in annular segments II, these.

latter cannow overcome the effect of the spring force transmittedl byjinner sleeve 5, interrupted ring I and outer sleeve 3, since the effects of setback cn these elements are Yno longer present. Annular segments II slide upthe inclined surface I2 of the cap I4, ,spread apart one from the other and press against the wall of the fuze body. From the drawing it isapparent that the outward movement of segments II moves sleeve 3 a; short distance forward.l Striker 1, already relieved from the inuence of the spring, is now entirely free. The fuze is now armed and striker l' can set off the explosive. action upon percussion of the shell.v

However, outer sleeve 3 is stillV maintained in itsforward position by annular segments II, innersleeve 5 is still clamped inouter 'sleeve 3. by thel action of interrupted ring I, and spring 9 is still compressed'in its extreme forward position.

Presently, interrupted ring I in `cooperation with spring 9 is going to act as an angular velocity detector.` During the flight of the shell, its

' angular velocity continuesr to decrease and there will comejan instant at which the action ofspring 9`overcomesthe outward pressure of interrupted ring l.

The dimensions of interrupted ring` I, the shape of inclined surface 2, and the force of spring 9,

are'chosen' in combination in such a mannerthat when 'therotational'speed.or angular velocity of theshell decreases to a predetermined value, obtained'previously by c alculationfor experience, the centrifugal forces generated.- in interrupted ring'fl" have `decreased until they areno longer sufficient to overcome .the force exerted by spring 9L At thisl moment. either the. interrupted ring closes up, or. its segments, move toward each other (dependinglon whether the ring isinterrupted in one placer only or in several places), until the overall diameter `ofsaicl .interrupted ring equalstheinside diameter of the rear part of .external lsleeve .3` (RI) Internal sleeve 5 thus becomes unlocked from external sleeve .3, permitting spring 9 to move internal sleeve 5. rapidly rearwards, carrying withit striker 1 engaged by itsshoulder 8.- Pinl sets Voif'the` explosive action causing self-destruction of the shell.

If, on the contrary, ,owingjto an insuflicient charge of vpropellaiitfor. instance,4 or for any other reason, theangular velocity of` the. projectile carrying 'fuze does notreachiatprescribed'nini mum value, the annular segments" vIfIfand/inthe split-ring lll, render a prematured explosion impossible. For this purpose, the mass of annular segments ll and their conical part, as Well as the slope of conical surface l2 of the cap, are chosen such that so long as the axial velocity of the projectile has not reached said minimum prescribed value, (even if split-ring l has already spread), the centrifugal forces generated in annular segments il remain insufcient to overcome the axial force exerted backwards on said annular segments il by spring 9 (through the medium of inner sleeve 5, centrifugally controlled elements i, and outer sleeve 3). Even in the case where, through lack of velocity, the projectile shouid drop but a few feet away from the gun, no explosion would take place.

It may be seen readily, that interrupted ring l must satisfy two geometrical conditions:

(a) Its radial thickness T must be slightly less than the difference existing betwen radii R2 and Rl in order to permit the sliding of inner shell 5 in its lodging in outer sleeve 3;

(b) Its rear end must be provided with a surface inclined toward the axis, in order to make it possible for inner sleeve 5 to become locked in its lodging in outer sleeve 3.

Attention is directed to the efficiency of use of the annular space which is usually provided to house the commonly used elements called upon to perform similar functions, and in particular it should be noted that, for the same overall dimensions of the space leftl free for this purpose, the interrupted ring I' may be made much heavier than the usual spherical, cylindrical or prismatic bodies which are intended for radial displacement.

Further, the usual cylindrical or prismatic bodies would have available for their guiding only a distance equal to the radial dimension T diminished by the amount needed by their rounded off portion and the distance of travel, that is, in short, somewhat less than said radial dimension T, while on the contrary, in the case of a ring interrupted in two places as described, for instance, the annular segments could be guided on a distance somewhat smaller than the internal radius Rl of outer sleeve 3; expressed more exactly, this guiding distance could be equal to said radius Ri diminished by the amount of radial travel.

The two just mentioned characteristics of the described centrifugally controlled elements, i. e. their relatively large Weight and long guiding distance result in great ease in manufacturing and assembling, while obtained a high degree of reliability in the functioning of the angular velocity detecting device. Such a device, when used as shown in a projectile fuze in conjunction with the usual booster arrangement causing the explosion of the projectile at its percussion, will result in a combined mechanical fuze meant both for explosion at percussion and for self-destruction, the reliability of the latter performance being greater than that obtained heretofore.

It should be pointed out that the invention disclosed herein has been described only in an illustrative sense and that it is obvious that the invention is capable of a variety of embodiments. It is my intention to cover all of the modiiications and embodiments of the invention falling within the inventive concept as described by the appended claims.

I claim:

1. In a mechanical fuse of the percussion and self destruction type for use in a rotating projectile, and having a movable firing pin, centrifugally operable means blocking movement of said pin to firing position when in unarmed position and movable by centrifugal force to armed position in which said means lie clear of the path of movement of the pin, detent means, a movable coupling element interposed between said iiring pin and said detent means, means by which movement of said coupling element in the direction of firing movement of said pin moves said pin, but which leaves said pin free to move to ring position independently by contact with a target, and spring means urging said coupling element in the direction of rng movement of the firing pin, the novel feature comprising a circumferential groove on said coupling element, and a ring in said groove, said ring being split radially in at least one place, and being engageable with said detent means by opening under the iniiuence of centrifugal force to retain said coupling element and thereby said firing pin against movement by said spring means to ring position as long as the rotational velocity of the projectile carrying the fuse remains greater than a predetermined magnitude, said detent means having a sloping surface, and a cooperating sloping surface on said ring, said cooperating sloping surfaces comprising cam means by which said ring is moved to a non-retaining position by pressure of said spring means on said coupling element when the rotational velocity of the projectile decreases from its peak to said predetermined magnitude.

2. The fuse structure set forth in claim 1, said detent means comprising a sleeve surrounding said coupling means and said ring pin, said sleeve being slidable parallel with said firing pin, a base for the fuse, said base having on its inner surface a bevel edged depression, said centrifugally operable means having a beveled edge about its lower portion and lying at least partly within said depression when in said unarmed position, the rear end of said sleeve extending into contact with said centrifugally operable means, when said sleeve is in its rearmost position, and second centrifugally operable means engaging the rear end of said sleeve when the fuse is in unarmed condition and maintaining said sleeve in a position which retains said first centrifugally operable means in said depression, whereby release of said sleeve by the action of centrifugal force on said second centrifugally operable means frees said sleeve for forward movement as the effects of centrifugal force on said rst centrifugally operable means forces said means radially outwardly over the beveled edge of said depression.

WILLI WEISS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,380,774 Clay June '7, 1921 1,956,222 Methlin Apr. 24, 1934 2,335,842 Nichols Nov, 30, 1943 2,405,653 Honger Aug. 13, 1946 

